The objective is to design, build, and clinically assess an Adaptive Wireless Computer Mouse (AWCM) for movement disorders. Development will focus on Parkinson's disease (PD) and essential tremor (ET). Major symptoms of PD include tremor, dyskinesias, bradykinesia, and rigidity. ET produces tremors that affect motor function. Symptoms from these diseases have a large effect on upper extremity motor control for afflicted patients. One activity affected is using a mouse for computer cursor control. A standard computer mouse translates user hand movement to cursor position on the computer display. PD and ET symptoms create noise that can mask user intention information. Noise may be in the form of involuntary movements such as tremor or dyskinesias or in the form of difficulty in initiating movements from bradykinesia or rigidity. The specific aim of this proposal is to develop and assess an AWCM that can detect a specific movement disorder symptom and provide compensation. The proposed AWCM is a wearable computer accessory to enhance computer and Internet access for those with movement disorders. This proposed assistive device would allow individuals to maintain their sense of computer independence, remain computer proficient at work/home, and may improve their social, economic, and learning capabilities